[Difficulties in using archival paraffin-embedded tissues for RNA expression analysis].

Formalin-fixed and paraffin-embedded tissue sections are used for routine histopathological diagnostics, but they have increasingly become material for molecular studies of genome and gene expression using molecular biological techniques such as PCR and RT-PCR. A major limitation is the significant degree of degradation and chemical modification of the nucleic acids recovered from fixed tissues. The purpose of this review is to provide an overview of studies on the possibility of using routinely prepared paraffin-embedded tissue sections as a source of messenger RNA. Difficulties in recovering high-quality RNA are mainly connected with the influence of formalin on nucleic acids and the effects of other physical and chemical agents on tissue during preservation and fixation. It is necessary to optimize RNA isolation and polymerase chain reaction conditions. Special attention is paid to the rising need to introduce alternative techniques for the fixation of tissue sections that provide for better preservation of both macromolecules and tissue morphology and for conducting histological diagnostics with molecular studies.